THE RED MASON BEE (and relatives).

Bees in general are very important insects: every third mouthful of our food is dependent on bees as pollinators of the plants we eat. This is because they are needed to pollinate flowers. Insects are by far the most important pollinators. These include moths, butterflies, beetles, flies and some wasps, but the most important pollinators of all are the bees : most species of insect-pollinated plants are specialised for pollination by bees. Bees are the best pollinators because they actively collect pollen as food for their larvae and they have evolved special structures on their bodies for handling and transporting pollen. And in the economy of nature, producing an excess of pollen, together with sweet nectar, is the price that plants pay in return for the pollination services provided by the bees.
The Red Mason Bee (Osmia rufa)
The Red Mason Bee is widespread in England and Wales and particularly likes the range of flowers and trees found in domestic gardens. It is a more efficient pollinator of fruit crops than the honeybee and by attracting them to your garden not only will you notice improved fruit crops - apples, plums, pears, strawberries and raspberries - but the bees also visit a wide range of garden flowers.
Life History
The Red Mason Bee is a solitary bee. That is, each nest tube is the work of a single female working alone. Unlike the honeybees and bumblebees, there is no worker caste of sterile females, so she receives no help from other bees; there is no colony or "hive". The species has an annual life cycle and they are active from late March to the beginning of July. Males and females emerge in early spring (late March to April) and mate. Females then seek out suitable nest sites usually beetle borings in deadwood, hollow plant stems, or irregular cavities in stones and old walls. Each nest tube comprises a series of cells. The female starts her first cell at the back of the nest. She makes 10 to 15 foraging trips to collect sufficient pollen to provision each cell. The pollen is mixed with a little nectar and this acts as a food source for the single egg, which she lays immediate-ly before sealing the cell with a mud partition. The process is repeated until the tube is filled with a row of about 6 to 10 cells. They also close the completed nest with mud. This is why they are called "mason" bees. Females finish nesting in early July. Being a solitary species they will never live to see their offspring. However in the comfort of their nests, the eggs hatch into larvae, which feed on the pollen/nectar mixture. After moulting 4 or 5 times, the full-grown larvae spin a tough brown silk cocoon and pupate. The new adults form in September and remain in the cocoon until the following spring when the new generation of adults emerge and the cycle begins again. Although solitary, mason bees are attracted to each other. They like to build their nests in aggregations and females tend to nest close to where they emerge. The design of the Oxford Bee Company Ltd nest box (see next page) is such that it will attract a number of nesting females, many of whose daughters will re-use their natal nests the following season. Thus a permanent nesting population will be established in your garden.
As with other solitary bees, mason bees are gentle and shy. They do have a sting but they use it only if they are caught and very roughly handled. They are docile simply because, unlike the honeybee, they do not make and store large amounts of honey and therefore do not have a huge resource to protect.
Busy bees
Research has shown that one female Osmia rufa does the pollination work of between 120 and 160 honeybees. Osmia species are, bee-for-bee, much more efficient pollinators of fruit trees than the honeybee for the following reasons:
1) Osmia can fly in chilly weather and are often busy pollinating when the honeybee is still in the hive.
2) At any given temperature, Osmia visits more flowers per minute than honeybees.
3) On any given foraging trip, Osmia is more promiscuous than the honeybee in terms of the number of trees visited and hence effects more cross-pollination.
4) Osmia females carry their pollen dry on a dense brush of hairs under the abdomen and are not very efficient at grooming themselves. By contrast, the honeybee compacts its pollen loads on to the hind legs, moistened with nectar and is very good at grooming itself. Thus, for anatomical and behavioural reasons, with Osmia there is a greater chance of loose pollen being transferred from one fruit blossom to another than there is with the honeybee.
Osmia is almost entirely pollen driven: mason bees do not store honey and so actively scrabble for pollen at every flower visit, unlike the honeybee, which is equally interested in collecting large amounts of nectar and often lands on the sides of fruit flowers to gain access to nectaries, with minimal contact with pollen-bearing anthers.
Native UK Bees Enhance Your Garden but They Need Homes
Besides the honeybee, Britain has more than 250 species of native bee, many of which help your garden by pollinating flowers. But these bees are becoming scarce as modern agriculture has produced a landscape that is rarely bee-friendly these days. With fewer wild flowers and suitable nest sites, about 25 per cent of our native bees are now endangered species. In addition traditional apiculture has been badly hit by the Varroa mite so it is vital to find additional managed pollinators to complement the honey bee. Importantly, mason bees are not susceptible to the Varroa mite.
Janet Keene (from information supplied by Chris O'Toole)

Bee Nest Boxes

Sturdy nest boxes can be bought from CJ WildBird Foods . All you need to do is place them in sunny, sheltered, south-facing position in the garden and you will attract nest-seeking females of the red mason bee in early spring. No work is required - if the nest boxes are in the garden at the right time the bees will find them. Because they like similar nest sites you could be lucky and also attract the blue mason bee (Osmia coerulescens) and two species of leaf-cutter bees (Megachile spp.). The nest tubes mimic the natural nest sites of these bees: beetle borings in dead wood and hollow plant stems.